There is an entire Stack Exchange site dedicated to these topics: Computational Science Stack Exchange. Their help center doesn't mention Scilab in their list of software packages or languages used broadly in computational science, but it seems to fit the bill.
Yes, automata questions are considered on topic here. Regarding whether you should ask here or on CS, I would recommend asking wherever you think the question has a better chance of getting a good answer.
Non-moderators can only vote to migrate questions to a small set of predefined sites. On Math.SE, the set of potential migration targets consists of Physics.SE and Stats.SE (plus meta).
Stack Exchange staff can add migration targets (up to 5, but few sites have that many). As a matter of general policy, beta sites are not added as migration targets.
I have also noticed this issue. For various reasons, users often use the tag for questions that are on topic here but which were encountered in the context of computer science, even if the questions is completely mathematics.
Why does a complete binary tree of $n$ leaves have $2n-1$ nodes?
How are the full semantics of SOL and HOL specified?
Most of the ...